1. Field of the Invention
The present invention relates to a universal joint shaft, and in particular to an improved universal joint shaft which is capable of implementing an easier assembling and installation and decreasing a fabrication cost by improving the structure of a shaft which is installed between yokes for transferring a rotational force.
2. Description of the Background Art
Generally, a universal joint shaft is installed in an inclined state at a certain angle for thereby transferring a rotational force. The universal joint includes a yoke engaged to a side which transfers a rotational force and a side which receives the same, and a shaft which transfers a rotational force between the yokes.
The shaft is implemented in various types for effectively transferring a rotational force between the yokes. Generally, a slip joint which is formed of two shafts and slips in an axial direction for an easier installation of a universal joint shaft is used.
The above universal joint shaft is generally used for a steering apparatus of a vehicle. Recently, each part of the steering apparatus is fabricated in a module type. Therefore, the universal joint shaft is installed between a column module and a chassis module.
Namely, the universal joint shaft is installed between the column module engaged with a steering wheel and a steering column for generating a rotational force, and the chassis module engaged with a gear box and a suspension for operating a wheel.
FIG. 1 is a view illustrating a conventional universal joint shaft. As shown therein, yokes 2 and 3 installed at both sides are classified into a driving yoke 2 connected with a member which generates a rotational force and a driven yoke 3 which is connected with a member for receiving a rotational force.
In addition, an elongated shaft is installed between the yokes 2 and 3 for transferring a rotational force therebetween. The shaft is divided into two shafts and is formed of a slip joint capable of implementing a transfer of a rotational force and a slipping operation in an axial direction.
The slip joint 4 includes a driving shaft 5 connected with the driving yoke 2 and a driven shaft 6 connected with the driven yoke 3. A part of the driven shaft 6 is inserted into a hollow inner portion of the driving shaft 5.
A pair of serrations 5a and 5b(or splines) are formed in an inner surface of the driving yoke 2 and an outer surface of the driven yoke 3 and are engaged in a rotation direction for thereby implementing a rotational force transfer and an axial direction slip.
Namely, the slip joint 4 slips, so that a difference between an actual installation distance and a design distance is compensated and is inserted between a member which transfers a rotational force and a member which receives the same in a retracted state and then is extended for thereby implementing an easier assembling operation of the universal joint shaft 1.
A pair of slits 5b are formed in both front end sides of the driving shaft 5 into which the driven shaft 6 is inserted, and a part of each of the slits 5b is cut. A clip 7 is installed in an outer portion of the slit 5b for pressing the driving shaft 5.
A dust cap 8 is installed at a front end of the opened driving shaft 5 for preventing a foreign substance and dusts from being introduced between the slipping driving shaft 5 and the driven shaft 6.
In the thusly constituted conventional universal joint shaft, in a state that the dust cap 8 and the clip 7 are installed in an outer portion of the driving shaft 5, respectively, the driving yoke 2 engaged with the driving shaft 5 is installed in a member which generates a rotational force, and the driven yoke 3 engaged with the driven shaft 6 is installed in a member which receives the rotational force.
In addition, the driven shaft 6 is inserted into the interior of the driving shaft 5. The portion between the driving shaft 5 and the driven shaft 6 is distanced so that an opened front end of the driving shaft 5 is opposite to the front end of the driven shaft 6 inserted thereinto.
In a state that the driven shaft 6 is inserted into the front end of the driving shaft 5, the driving shaft 5 and the driven shaft 6 are moved in an axial direction to match with the installation length for thereby adjusting the axial direction length of the slip joint 4.
In a state that the axial direction length is adjusted, a clip 7 is installed in an outer portion of the slit 5b of the driving haft 5, and a dust cap 8 is installed in a front end of the driving shaft 5.
As described above, the conventional universal joint shaft has the following problems due to an adaptation of the slip joint.
First, since a serration and spline structure is needed in an inner surface of the driving shaft and an outer surface of the driven shaft, the construction of the system is complicated.
Next, since the driving shaft and driven shaft are engaged, and the portions capable of implementing a stable supporting force in a rotational direction are increased, the length of the same is too extended.
In addition, a clip is installed for engaging the driving shaft and the driven shaft. A dust cap is installed for preventing dusts and foreign substances from being introduced. Here, it is very difficult to install the clip and dust cap.
The driving yoke having the driving shaft is installed in a member which generates a rotational force. The driven yoke having the driven shaft is installed in a member which receives a rotational force. For engaging the driving shaft and the driven shaft, the driving shaft and the driven shaft must be moved in an axial direction. Therefore, the processes are additionally needed. Therefore, an installation space is increased.
In particular, when installing a steering apparatus of a vehicle, the column module engaged with the driving yoke must be moved in the upper and lower direction of the axial direction.
Therefore, in the conventional universal joint shaft, the construction of the same is complicated, and the length is long. The fabrication of the same is difficult. The process of the fabrications is increased. An installation space is increased. It is difficult to implement an assembling, installation and module. Therefore, the fabrication cost is increased.
Accordingly, it is an object of the present invention to provide a universal joint haft which overcomes the problems encountered in the conventional art.
It is another object of the present invention to provide a universal joint shaft which is capable of installing a driving yoke and a driven yoke in a certain installation position, distancing the front ends of a driving shaft and a driven shaft connected with a driving yoke and a driven yoke, respectively, for easily engaging the shafts in a state that the driving yoke and the driven yoke is not distanced, preparing a connection shaft therebetween and forming a rectangular cross section the driving shaft, the driven shaft and the connection shaft, respectively, for thereby implementing an easier assembling, installation and module, so that it is possible to decrease the fabrication cost.
To achieve the above objects, there is provided a universal joint shaft which includes a driving shaft and driven shaft engaged to a driving yoke and driven yoke which are arranged in an installation position and have opposite both front ends which are distanced and a rectangular cross section in a radius direction, and a three-divided joint formed of connection shafts and having a cross section in a radius direction to correspond to the driving shaft and driven shaft for implementing a radius direction slip and rotational force transfer between the driving shaft and the driven shaft, wherein the universal joint shaft includes a driving yoke and a driven yoke for transferring a rotational force in an inclined state at a certain angle.